<?php
/**
 * PHPExcel
 *
 * Copyright (c) 2006 - 2011 PHPExcel
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 *
 * @category   PHPExcel
 * @package    PHPExcel_Shared_Best_Fit
 * @copyright  Copyright (c) 2006 - 2011 PHPExcel (http://www.codeplex.com/PHPExcel)
 * @license    http://www.gnu.org/licenses/old-licenses/lgpl-2.1.txt    LGPL
 * @version    1.7.6, 2011-02-27
 */


/**
 * PHPExcel_Best_Fit
 *
 * @category   PHPExcel
 * @package    PHPExcel_Shared_Best_Fit
 * @copyright  Copyright (c) 2006 - 2011 PHPExcel (http://www.codeplex.com/PHPExcel)
 */
class PHPExcel_Best_Fit
{
    protected $_error                = False;

    protected $_bestFitType            = 'undetermined';

    protected $_valueCount            = 0;

    protected $_xValues                = array();

    protected $_yValues                = array();

    protected $_adjustToZero        = False;

    protected $_yBestFitValues        = array();

    protected $_goodnessOfFit         = 1;

    protected $_stdevOfResiduals    = 0;

    protected $_covariance            = 0;

    protected $_correlation            = 0;

    protected $_SSRegression        = 0;

    protected $_SSResiduals            = 0;

    protected $_DFResiduals            = 0;

    protected $_F                    = 0;

    protected $_slope                = 0;

    protected $_slopeSE                = 0;

    protected $_intersect            = 0;

    protected $_intersectSE            = 0;

    protected $_Xoffset                = 0;

    protected $_Yoffset                = 0;


    public function getError() {
        return $this->_error;
    }    //    function getBestFitType()


    public function getBestFitType() {
        return $this->_bestFitType;
    }    //    function getBestFitType()


    public function getValueOfYForX($xValue) {
        return False;
    }    //    function getValueOfYForX()


    public function getValueOfXForY($yValue) {
        return False;
    }    //    function getValueOfXForY()


    public function getXValues() {
        return $this->_xValues;
    }    //    function getValueOfXForY()


    public function getEquation($dp=0) {
        return False;
    }    //    function getEquation()


    public function getSlope($dp=0) {
        if ($dp != 0) {
            return round($this->_slope,$dp);
        }
        return $this->_slope;
    }    //    function getSlope()


    public function getSlopeSE($dp=0) {
        if ($dp != 0) {
            return round($this->_slopeSE,$dp);
        }
        return $this->_slopeSE;
    }    //    function getSlopeSE()


    public function getIntersect($dp=0) {
        if ($dp != 0) {
            return round($this->_intersect,$dp);
        }
        return $this->_intersect;
    }    //    function getIntersect()


    public function getIntersectSE($dp=0) {
        if ($dp != 0) {
            return round($this->_intersectSE,$dp);
        }
        return $this->_intersectSE;
    }    //    function getIntersectSE()


    public function getGoodnessOfFit($dp=0) {
        if ($dp != 0) {
            return round($this->_goodnessOfFit,$dp);
        }
        return $this->_goodnessOfFit;
    }    //    function getGoodnessOfFit()


    public function getGoodnessOfFitPercent($dp=0) {
        if ($dp != 0) {
            return round($this->_goodnessOfFit * 100,$dp);
        }
        return $this->_goodnessOfFit * 100;
    }    //    function getGoodnessOfFitPercent()


    public function getStdevOfResiduals($dp=0) {
        if ($dp != 0) {
            return round($this->_stdevOfResiduals,$dp);
        }
        return $this->_stdevOfResiduals;
    }    //    function getStdevOfResiduals()


    public function getSSRegression($dp=0) {
        if ($dp != 0) {
            return round($this->_SSRegression,$dp);
        }
        return $this->_SSRegression;
    }    //    function getSSRegression()


    public function getSSResiduals($dp=0) {
        if ($dp != 0) {
            return round($this->_SSResiduals,$dp);
        }
        return $this->_SSResiduals;
    }    //    function getSSResiduals()


    public function getDFResiduals($dp=0) {
        if ($dp != 0) {
            return round($this->_DFResiduals,$dp);
        }
        return $this->_DFResiduals;
    }    //    function getDFResiduals()


    public function getF($dp=0) {
        if ($dp != 0) {
            return round($this->_F,$dp);
        }
        return $this->_F;
    }    //    function getF()


    public function getCovariance($dp=0) {
        if ($dp != 0) {
            return round($this->_covariance,$dp);
        }
        return $this->_covariance;
    }    //    function getCovariance()


    public function getCorrelation($dp=0) {
        if ($dp != 0) {
            return round($this->_correlation,$dp);
        }
        return $this->_correlation;
    }    //    function getCorrelation()


    public function getYBestFitValues() {
        return $this->_yBestFitValues;
    }    //    function getYBestFitValues()


    protected function _calculateGoodnessOfFit($sumX,$sumY,$sumX2,$sumY2,$sumXY,$meanX,$meanY, $const) {
        $SSres = $SScov = $SScor = $SStot = $SSsex = 0.0;
        foreach($this->_xValues as $xKey => $xValue) {
            $bestFitY = $this->_yBestFitValues[$xKey] = $this->getValueOfYForX($xValue);

            $SSres += ($this->_yValues[$xKey] - $bestFitY) * ($this->_yValues[$xKey] - $bestFitY);
            if ($const) {
                $SStot += ($this->_yValues[$xKey] - $meanY) * ($this->_yValues[$xKey] - $meanY);
            } else {
                $SStot += $this->_yValues[$xKey] * $this->_yValues[$xKey];
            }
            $SScov += ($this->_xValues[$xKey] - $meanX) * ($this->_yValues[$xKey] - $meanY);
            if ($const) {
                $SSsex += ($this->_xValues[$xKey] - $meanX) * ($this->_xValues[$xKey] - $meanX);
            } else {
                $SSsex += $this->_xValues[$xKey] * $this->_xValues[$xKey];
            }
        }

        $this->_SSResiduals = $SSres;
        $this->_DFResiduals = $this->_valueCount - 1 - $const;

        if ($this->_DFResiduals == 0.0) {
            $this->_stdevOfResiduals = 0.0;
        } else {
            $this->_stdevOfResiduals = sqrt($SSres / $this->_DFResiduals);
        }
        if (($SStot == 0.0) || ($SSres == $SStot)) {
            $this->_goodnessOfFit = 1;
        } else {
            $this->_goodnessOfFit = 1 - ($SSres / $SStot);
        }

        $this->_SSRegression = $this->_goodnessOfFit * $SStot;
        $this->_covariance = $SScov / $this->_valueCount;
        $this->_correlation = ($this->_valueCount * $sumXY - $sumX * $sumY) / sqrt(($this->_valueCount * $sumX2 - pow($sumX,2)) * ($this->_valueCount * $sumY2 - pow($sumY,2)));
        $this->_slopeSE = $this->_stdevOfResiduals / sqrt($SSsex);
        $this->_intersectSE = $this->_stdevOfResiduals * sqrt(1 / ($this->_valueCount - ($sumX * $sumX) / $sumX2));
        if ($this->_SSResiduals != 0.0) {
            if ($this->_DFResiduals == 0.0) {
                $this->_F = 0.0;
            } else {
                $this->_F = $this->_SSRegression / ($this->_SSResiduals / $this->_DFResiduals);
            }
        } else {
            if ($this->_DFResiduals == 0.0) {
                $this->_F = 0.0;
            } else {
                $this->_F = $this->_SSRegression / $this->_DFResiduals;
            }
        }
    }    //    function _calculateGoodnessOfFit()


    protected function _leastSquareFit($yValues, $xValues, $const) {
        // calculate sums
        $x_sum = array_sum($xValues);
        $y_sum = array_sum($yValues);
        $meanX = $x_sum / $this->_valueCount;
        $meanY = $y_sum / $this->_valueCount;
        $mBase = $mDivisor = $xx_sum = $xy_sum = $yy_sum = 0.0;
        for($i = 0; $i < $this->_valueCount; ++$i) {
            $xy_sum += $xValues[$i] * $yValues[$i];
            $xx_sum += $xValues[$i] * $xValues[$i];
            $yy_sum += $yValues[$i] * $yValues[$i];

            if ($const) {
                $mBase += ($xValues[$i] - $meanX) * ($yValues[$i] - $meanY);
                $mDivisor += ($xValues[$i] - $meanX) * ($xValues[$i] - $meanX);
            } else {
                $mBase += $xValues[$i] * $yValues[$i];
                $mDivisor += $xValues[$i] * $xValues[$i];
            }
        }

        // calculate slope
//        $this->_slope = (($this->_valueCount * $xy_sum) - ($x_sum * $y_sum)) / (($this->_valueCount * $xx_sum) - ($x_sum * $x_sum));
        $this->_slope = $mBase / $mDivisor;

        // calculate intersect
//        $this->_intersect = ($y_sum - ($this->_slope * $x_sum)) / $this->_valueCount;
        if ($const) {
            $this->_intersect = $meanY - ($this->_slope * $meanX);
        } else {
            $this->_intersect = 0;
        }

        $this->_calculateGoodnessOfFit($x_sum,$y_sum,$xx_sum,$yy_sum,$xy_sum,$meanX,$meanY,$const);
    }    //    function _leastSquareFit()


    function __construct($yValues, $xValues=array(), $const=True) {
        //    Calculate number of points
        $nY = count($yValues);
        $nX = count($xValues);

        //    Define X Values if necessary
        if ($nX == 0) {
            $xValues = range(1,$nY);
            $nX = $nY;
        } elseif ($nY != $nX) {
            //    Ensure both arrays of points are the same size
            $this->_error = True;
            return False;
        }

        $this->_valueCount = $nY;
        $this->_xValues = $xValues;
        $this->_yValues = $yValues;
    }    //    function __construct()

}    //    class bestFit
